production · multiphase flow
Hydrate Risk Estimate
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Inputs
—
g/mol
%
Description
Estimates the hydrate-formation temperature depression achieved by a given concentration of methanol or MEG (monoethylene glycol) inhibitor in the water phase, using the Hammerschmidt (1939) equation — a simple, closed-form reduction of the more rigorous (chart-based) Katz K-factor method, suitable for a quick field estimate of inhibitor effectiveness or required injection concentration.
Variables
| Symbol | Unit | Description |
|---|---|---|
| ΔT | Δ°F | Hydrate Temperature Depression |
| K | — | Empirical inhibitor-specific constant: K=2335 for methanol, K=2700 for monoethylene glycol (MEG). Entered directly rather than selected from a list — the paired MW value below must match the same inhibitor. |
| MW | g/mol | Molecular weight of the inhibitor: 32.04 g/mol for methanol, 62.07 g/mol for MEG. Must be paired with the matching K value above. |
| w | % | Mass fraction (weight percent) of inhibitor in the final water phase. |
Assumptions
- The inhibitor is either methanol or MEG, entered via the correctly-paired (K, MW) values — mismatching K from one inhibitor with MW from another gives a meaningless result
- w is the mass fraction of inhibitor in the FINAL water phase (after mixing), not the injection concentration before mixing with produced/condensed water
Limitations
- Validity range is disclosed with two different framings found in the literature, not asserted confidently as one: the commonly-cited range is up to ~25 wt% methanol in the water/inhibitor phase (this calculator's own basis, flagged above 25% via a result flag); at least one source frames validity instead as a mol%-of-the-gas-stream basis (methanol <0.2 mol%, glycol <0.4 mol%) rather than a water-phase mass fraction — a materially different basis this calculator does not check, since the two framings are not simply interconvertible without additional gas-stream composition data
- A simplified reduction of the more rigorous Katz K-factor chart method — accuracy degrades at high pressure or for gas compositions significantly different from the conditions the original correlation was fit to
- Does not account for salinity in the water phase, which also depresses (or, combined with inhibitor, further affects) the hydrate formation temperature — a real complicating factor for produced water with significant salt content, not modeled here
- The primary source (Hammerschmidt, 1939, Industrial & Engineering Chemistry) is a pre-digital-era article, genuinely inaccessible — the formula and constants are corroborated across multiple independent public engineering sources instead, not page-confirmed against the original.
Use Cases
- → Inhibitor injection rate screening: Quickly estimate the temperature depression a candidate methanol or MEG concentration will achieve, before a more rigorous hydrate-curve/chart-based check.
- → Required concentration estimate: Back-solve (by iterating w) the approximate inhibitor concentration needed to achieve a target temperature depression for a given flowline's operating conditions.
Related Calculations
Region Notes
Global
Cold-weather and subsea/deepwater gathering systems are the most common candidates for hydrate risk — always cross-check a Hammerschmidt-based screening estimate against a proper hydrate-curve (pressure-temperature) analysis before finalizing an inhibitor injection design.
References
Primary source
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